Contact your Ga Cooperative extension service run by the University of GA. They have a lot of information already on their website on lawns in GA.
Sounds like you got stuck with the normal 3 trees, 9 bushes and dying grass that they put down in newer subdivisons. If so, then take advantage of it and consider that you have a clean slate to work with. Maybe consider not even having a lawn, but instead a ground cover that needs no mowing at all. There are many to choise from.
You do need a LOT of
compost to work into your soil to make it become healthy. Consider doing one area at a time until you have added 2-4 inches of compost into the different areas. Add plants one area at a time. In Atlanta GA, you can grow several warm season grasses if you want grass, including St. Augustine. Many grasses need lots of water, and there have been water restrictions in Atlanta before. Consider talking to the folks over at your County Solid Waste Department and read up on the information on Xeriscaping for your yard. Consider using lots of native plants as well. Many can be used in the Atlanta area, including edible ones like blueberries, and even strawberries for ground cover. Feed your family and the wildlife at the same time.